In copending application Ser. No. 07/138,771, entitled "Process for Prevention of Flyslag Deposits" by P. L. Zuideveld, attorney docket No. K-7631, filed even date herewith, and incorporated herein by reference, there is described a process for prevention or inhibition of deposits of flyslag particles on the surfaces of a heat exchange zone or equipment employed in cooling synthesis gas and flyslag particles produced from the gasification of coal or similar carbonaceous materials. Notwithstanding the practice of that invention, deposits of flyslag may occur on the heat exchange surfaces, for a variety of reasons. For example, on start-up of the process, before the required superficial velocities of the synthesis gas and flyslag particles are obtained, deposits may occur. If there are interruptions in the process flows, shutdown, or variations due to turndown of the gasification reaction, some deposition may occur. Accordingly, a procedure which may remove these deposits without interruption of the process might have great economic value. The invention concerns such a procedure.